Vending Machine Simulator

C++14 Console Simulator Built Without STL

Advanced C++ simulator using custom linked lists, the command pattern, and manual memory management verified leak-free with Valgrind.

C++14 · Custom Data Structures · Command Pattern

View Code

16+

Test Suites

Command Classes

Coin Denominations

Memory Leaks (Valgrind)

Project Overview

What It Does

A fully-functional C++14 vending machine for a fictional pastry company, focused on robust programming, clean code, and dynamic memory management. Operates entirely in a console environment with persistent file-backed storage.

Product display, purchases, stock management, coin handling, and admin operations
Strict input and file validation with meaningful error messages
Custom singly & doubly linked lists built from scratch (no STL containers)
Manual new/delete verified leak-free with Valgrind

Custom Data Structures

Data Structure Design

Abstract LinkedList base class with virtual printLL, findItem, saveLL, resetStock, remove, addLL, and deleteLL
LinkedListSingle: singly-linked list for inventory traversal
LinkedListDouble: doubly-linked list with prev/next pointers enabling reverse display
Node / NodeD classes encapsulating product data (ID, name, description, price, on-hand quantity)
Strategy-style runtime switching between the two list implementations

Core Features

Product Management

Display inventory ascending/descending, add items, remove stock, and track availability.

Transactions

Exact-change, insufficient-funds detection, out-of-stock handling, and transaction abort.

Coin System

Eight denominations (5¢ – $10) with a greedy change-dispensing algorithm.

File Persistence

Validated stock.dat / coins.dat with strict format checking.

Admin Functions

Reset coins, restock, reverse-display inventory, and abort transactions.

Runtime List Switching

Toggle between single and doubly linked lists at runtime via the strategy pattern.

Architecture

System Components

VendingMachine: core orchestrator managing state and command dispatch
Command Pattern: eight command classes (Abort, DisplayItem, PurchaseItem, Save, AddItem, RemoveItem, DisplayCoins, ResetCoins)
Menu: UI layer for command selection
Coin / Price: currency representation and change calculation
Helper: static validation utilities for stock/coin formats and input parsing

Testing & Quality Assurance

Coverage

16+ test suites covering all major features and edge cases
Functional & purchase tests: exact change, insufficient funds, out-of-stock, invalid selection
Admin tests: coin reset, restock, forward/reverse display, add/remove items
Edge cases: malformed files, invalid delimiters, negative values, empty input
Memory safety: zero leaks across all operations, verified by Valgrind